Is someone who has gone through an event that has disrupted the continuity of their consciousness and fundamentally altered it really the same person? Did Jeanna really survive, or did she die, but was replaced by someone new living in her old body?

Is someone who has gone through an event that has disrupted the continuity of their consciousness and fundamentally altered it really the same person? Did Jeanna really survive, or did she die, but was replaced by someone new living in her old body?